When someone sends a member a private message, the member gets notified via both the "Private messages" section on their profile menu and an email notification.
But when someone tags you, you'll just receive an email notification (if you select the relevant option on your Settings page). You may simply miss it especially when your inbox is loaded and also when someone tags you in a thread that you are not following. It would be wonderful if there could be a section on the profile menu for that sort of notifications as well.
iI requested more information.]
What I have in mind is more of a notification feed than an inbox, I think. I tried to design an example:
Let's suppose yesterday (2019-09-03) I logged into my account and visited Thread X either through the provided blue link in the feed or via the email notification. After I visited the target thread, the 2 notifications in the feed became unhighlighted automatically. Yesterday, I forgot to visit Thread Y:
Let's suppose today I deleted all my email notifications, including the one which was about User C and Thread Y. User C has been waiting for my input and I have not even noticed it!

The key point here is that there needs to be a mechanism for establishing a relation between visiting the target thread and the status of the notification (highlighted vs. unhighlighted). I don’t know if it's possible for their engineering team to implement it within the framework of this platform, but I can imagine such a method would work well.
Those who have chosen not to receive any emails would benefit from it. I'd say it could benefit email receivers, too, as I described in my example.